Dental products and procedures

Abstract

Polymeric shells which fit over one or more natural teeth to change the perceived color of the teeth, and optionally to provide orthodontic support. The shells can be prepared by thermoforming selected polymeric sheets which contain optical additives over a physical image of the teeth, or by depositing polymeric compositions containing optical additives over a physical image of the teeth, or by additive manufacturing based upon a digital image of the teeth. The optical additives cause the combination of the shell and the teeth to have a desired appearance. At least part of the shell preferably has transparency greater than 75%, particularly greater than 85%.

The invention claimed is: 
     
       1. A removable self-supporting shell which (a) fits closely to substantially the entire surface of the teeth of a user, (b) changes a perceived color of the teeth, and (c) comprises at least a first layer which contacts the teeth and a second or outermost layer, the first layer comprising a polymer and a first concentration of one or more optical additives, and the second layer comprising a polymer, (i) and one or more optical additives in a second concentration which is substantially less than the first concentration or (ii) that is free from optical additives. 
     
     
       2. A removable self-supporting shell according to  claim 1 , wherein the second layer is free from optical additives. 
     
     
       3. A removable self-supporting shell according to  claim 1 , wherein the first layer is not on the outside of the shell when the shell is fitted over the teeth and the second layer is on the outside of the shell when the shell is fitted over the teeth wherein the second concentration of the one or more optical additives in the second layer is less than the first concentration of optical additives. 
     
     
       4. A removable self-supporting shell according to  claim 1 , wherein the shell comprises a laminate comprising a layer which (i) contains an optical additive which is an optical brightener and (ii) is not part of the exterior surface of the shell. 
     
     
       5. A removable self-supporting shell according to  claim 1  which is for use in an orthodontic procedure and which has a flexural modulus of from 1000 to 3000 MPa. 
     
     
       6. A removable self-supporting shell according to  claim 5  which has a thickness of 0.5 to 0.8 mm. 
     
     
       7. A removable self-supporting shell according to  claim 1  which is for use in changing the appearance of the teeth and which has a flexural modulus of less than 1000 MPa. 
     
     
       8. A removable self-supporting shell according to  claim 7  which has a thickness of 0.2 to 0.6 mm. 
     
     
       9. A removable self-supporting shell according to  claim 1 , wherein a portion of the shell has a total visible light transmission greater than about 75%. 
     
     
       10. A removable self-supporting shell according to  claim 9 , wherein the portion of the shell having a total visible light transmission greater than about 75% extends over a gum line beyond the upper edge of the teeth and/or the lower edge of the teeth. 
     
     
       11. A self-supporting shell according to  claim 1 , wherein the shell is made by thermoforming. 
     
     
       12. A method of making the removable self-supporting shell according to  claim 1 , the method comprising thermoforming a sheet around a physical model of the teeth over which the shell is to be fitted, the sheet having at least the first layer and the second or outermost layer, the first layer comprising the polymer and the first concentration of one or more optical additives, and the second or outermost layer comprising the polymer (i) and one or more optical additives in a second concentration which is substantially less than the first concentration or (ii) that is free from optical additives. 
     
     
       13. A method of making the removable self-supporting shell according to  claim 12 , wherein the model of the teeth to which the shell is to be fitted is made by three-dimensional printing based on a digital image of the teeth.